Tandem thrust reverser with sliding rails

ABSTRACT

A pivot thrust reverser includes a first tandem pivot door subassembly comprising an inner panel and an outer panel. The inner panel and outer panel are connected by a first sliding rail. A second tandem pivot door subassembly is included comprising an inner panel and an outer panel. The inner panel and outer panel are connected by a second sliding rail.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a divisional of U.S. application Ser. No. 14/184,335filed Feb. 19, 2014, for “TANDEM THRUST REVERSER WITH SLIDING RAILS” byJ. Chandler and G. Suciu, which claims priority to U.S. ProvisionalPatent Application Ser. No. 61/768,160, entitled “ATR TANDEM THRUSTREVERSER,” filed Feb. 22, 2013, which is hereby incorporated byreference in its entirety. Priority is also claimed to U.S. ProvisionalPatent Applications Ser. Nos. 61/768,154, entitled “ATR PIVOT THRUSTREVERSER WITH CONTOURING AROUND CORE,” filed Feb. 22, 2013; 61/768,166,entitled “ATR TANDEM THRUST REVERSER WITH 4-BAR LINKAGE,” filed Feb. 22,2013; 61/768,171, entitled “ATR CONTOURED THRUST REVERSER WITH 3 POINTACUATION,” filed Feb. 22, 2013; and 61/768,172, entitled “AIR TANDEMTHRUST REVERSER WITH 3 POINT ACTUATION,” filed Feb. 22, 2013. All ofthese are hereby incorporated by reference in their entirety.

BACKGROUND

The presently disclosed embodiments relate generally to gas turbineengine and/or nacelle assemblies and, more particularly, to thrustreversers used in gas turbine engine and/or nacelle assemblies.

Thrust reversers in gas turbine engine and/or nacelle assemblies aredeployed to redirect an aircraft's propulsive air flow, such as in aforward direction rather than aft. This can provide deceleration for theaircraft which, for example, can assist in slowing the aircraft downduring landing, and therefore, enable shorter landing distances whilereducing stress and wear on an aircraft's brakes. Thrust reversers areparticularly useful when a landing surface is icy or wet, andconsequently, the aircraft's brakes are less effective.

Commercial gas turbine engines typically include an engine whichproduces high temperature, high pressure exhaust ejected through anozzle downstream of the engine, and a bypass duct, which is generallyan annular space concentrically located about the engine through whichair from the engine fan, known as the fan bypass stream, is passed. Manyaircraft applications use high bypass ratio gas turbine engines, where amajority of the aircraft's propulsion is provided by the fan bypassstream, rather than by the exhaust produced from the engine. In suchapplications, a thrust reverser may be able to operate effectively byredirecting the fan bypass stream alone.

However, providing a thrust reverser to redirect the fan bypass streampresents design challenges. The thrust reverser must be part of anoverall aerodynamic design when stowed, yet be capable of effectivelydeploying at an appropriate angle which captures enough of the fanbypass stream, and redirects this fan bypass stream at the needed angle,to provide deceleration. Achieving this can be complicated due tostationary portions of the nacelle, which can serve as an obstruction tothe thrust reverser when attempting to move to the deployed position. Toobtain thrust reverser designs which provide the necessary decelerationand avoid nacelle interference, complex assemblies with a multitude ofparts have generally been used, often requiring translating partsrelative to the engine to allow the thrust reverser to deploy at aneffective location without nacelle interference. These designs also havegenerally included an obstruction present in the fan bypass streamreversal flow path, such as actuators or linkages. Moreover, thesecomplex designs are less reliable and require greater maintenance costs.Even with these complex designs, significant portions of the fan bypassstream are not redirected, resulting in a less efficient thrust reverserand, as a consequence, the need for longer landing distances andincreased wear on the aircraft's brakes.

SUMMARY

One embodiment includes a pivot thrust reverser. The pivot thrustreverser includes a first tandem pivot door subassembly comprising aninner panel and an outer panel. The inner panel and outer panel areconnected by a first sliding rail. A second tandem pivot doorsubassembly is included comprising an inner panel and an outer panel.The inner panel and outer panel are connected by a second sliding rail.

Another embodiment includes a method for use with a gas turbine engine.A first tandem pivot door subassembly is provided comprising an innerpanel and an outer panel. The inner panel and the outer panel of thefirst tandem pivot door subassembly are connected by a first slidingrail.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of an embodiment of a gas turbine engineand nacelle assembly with a pivot thrust reverser according to thepresent invention, shown in a stowed position.

FIG. 1B is a perspective view of the gas turbine engine and nacelleassembly of FIG. 1A with the pivot thrust reverser shown in a deployedposition.

FIG. 1C is an aft elevation view of the gas turbine engine and nacelleof FIG. 1B with interior structures of the engine omitted.

FIG. 2 is a perspective view of the pivot thrust reverser, with a singleactuator, in the deployed position showing the inner panels connected tothe outer panels by sliding rails.

FIG. 3 is an exploded perspective view of an inner panel and an outerpanel of a tandem pivot door subassembly.

FIG. 4A is a plan view of the actuator and tandem pivot doorsubassembly, shown in isolation, in the stowed position.

FIG. 4B is a plan view of the actuator and tandem pivot doorsubassembly, shown in isolation, in the deployed position.

FIG. 5A is a perspective view of a gas turbine engine and nacelleassembly with another embodiment of a pivot thrust reverser according tothe present invention, shown in a stowed position.

FIG. 5B is a perspective view of the gas turbine engine and nacelleassembly of FIG. 5A with the pivot thrust reverser shown in a deployedposition.

While the above-identified drawing figures set forth embodiments of theinvention, other embodiments are also contemplated. In all cases, thisdisclosure presents the invention by way of representation and notlimitation. It should be understood that numerous other modificationsand embodiments can be devised by those skilled in the art, which fallwithin the scope and spirit of the principles of the invention. Thefigures may not be drawn to scale, and applications and embodiments ofthe present invention may include features and components notspecifically shown in the drawings.

DETAILED DESCRIPTION

Generally, a pivot thrust reverser can be deployed to circumferentiallysurround (or, synonymously, contour around) a portion of a gas turbineengine inner bypass duct wall such that a fan bypass stream isinterrupted and redirected with relatively little leakage, while a corestream and a nacelle ventilation stream are unobstructed orsubstantially unobstructed. To avoid interference with the nacelle, thepivot thrust reverser uses a tandem pivot door subassembly with an innerpanel and an outer panel that rotate simultaneously about differentpivot points to allow the tandem pivot door subassembly to deploy andcircumferentially surround the inner surface of the bypass duct. Whenstowed, the pivot thrust reverser tandem pivot door subassembly makes upa portion of both a surface of a bypass duct (e.g., an outer duct wall)and an outer surface of a nacelle. The thrust reverser tandem pivot doorsubassembly can be pivotally deployed from a stowed position to adeployed position by a single actuator on pivot axes that arepositionally fixed relative to the gas turbine engine.

FIGS. 1A, 1B, and 1C show an embodiment of gas turbine engine andnacelle assembly 10. FIG. 1A is a perspective view of assembly 10 withpivot thrust reverser 20 in the stowed position. FIG. 1B shows aperspective view of assembly 10 with pivot thrust reverser 20 in adeployed position. FIG. 1C is an aft elevation view of assembly 10 shownwith pivot thrust reverser 20 in the deployed position. Assembly 10includes nacelle 12, outer surface 14 of nacelle 12, pylon 16, engine18, nacelle opening 19, pivot thrust reverser 20 with first tandem pivotdoor subassembly 22 and second tandem pivot door subassembly 24, bypassduct 26, outer surface 28 and inner surface 30 of bypass duct 26, innerpanel 31 and outer panel 32 of first tandem pivot door subassembly 22,first sliding rail 33, inner panel 34 and outer panel 35 of secondtandem pivot door subassembly 24, second sliding rail 36, upperbifurcation (bi-fi) fairing 40, lower bi-fi fairing 42, linkages 44 and48 of first tandem pivot door subassembly 22, linkages 46 and 50 ofsecond tandem pivot door subassembly 24, pivot axis 45 of inner panel31, pivot axis 47 of inner panel 34, pivot axis 49 of outer panel 32,pivot axis 51 of outer panel 35, actuator 52, fixed pivot connectionpoints 53 a and 53 b, fixed pivot connection points 54 a and 54 b, fanbypass stream F₁, redirected fan bypass stream F_(1′), nacelleventilation stream F₂, and core stream F₃. Certain components ofassembly 10, such as a fan of engine 18, have been omitted forsimplicity. Nacelle 12 provides an annular housing within which asubstantial portion of engine 18 is located. Engine 18 is aligned onaxis A of assembly 10 in the illustrated embodiment. Engine 18 includesa compressor section, a combustor section, and a turbine section (thosesections not specifically shown), which in combination produce hotcombustion gases that provide operational energy for engine 18. Pylon 16provides a means for mounting assembly 10 to an aircraft (not shown).Pivot thrust reverser 20 includes both first tandem pivot doorsubassembly 22 and second tandem pivot door subassembly 24. As shownhere, second tandem pivot door subassembly 24 is spaced approximately180° from first tandem pivot door subassembly 22 relative to axis A ofassembly 10.

When stowed, as shown in FIG. 1A, first tandem pivot door subassembly 22and second tandem pivot door subassembly 24 each form a portion of outersurface 14, such that outer surface 14 is substantially smooth at allpoints along an exterior of nacelle 12, including interfaces with firsttandem pivot door subassembly 22 and second tandem pivot doorsubassembly 24. Because first tandem pivot door subassembly 22 andsecond tandem pivot door subassembly 24 provide a smooth outer surface14 of nacelle 12, pivot thrust reverser 20 tends to reduce a risk ofundesired aerodynamic concerns.

Inner surface 30 of bypass duct 26 provides an outer surface of a wallcovering engine 18. Bypass duct 26 is defined by the annular spacewithin nacelle 12 between outer surface 30 and outer surface 28 ofbypass duct 26. Outer surface 28 of bypass duct 26 is formed by both aduct wall at the interior of nacelle 12 and first tandem pivot doorsubassembly 22 and second tandem pivot door subassembly 24 when in thestowed position at opening 19, as was shown in FIG. 1A. Inner panel 31and outer panel 32 of first tandem pivot door subassembly 22 areconnected by parallel sliding rails (e.g., two sliding rails) in thisembodiment. However only first sliding rail 33 is visible in FIG. 1B.Inner panel 34 and outer panel 35 of second tandem pivot doorsubassembly 24 are also connected by parallel sliding rails in thisembodiment. However, only second sliding rail 36 is visible in FIG. 1B(the other sliding rails are visible in FIG. 2). In other embodiments,the connection between inner panels 31 and 34 and outer panels 32 and 35can be made by a single sliding rail or more than two sliding rails, andthe sliding rails can be located in places at interfaces between innerpanels 31 and 34 and outer panels 32 and 35 as desired for particularapplications.

Both first tandem pivot door subassembly 22 and second tandem pivot doorsubassembly 24 can pivot on respective pivot axes that are eachpositionally fixed relative to their respective mounting locations.Thus, first tandem pivot door subassembly 22 and second tandem pivotdoor subassembly 24 can merely pivot into the deployed position, withoutrequiring any translation of portions of nacelle 12, first tandem pivotdoor subassembly 22, or second tandem pivot door subassembly 24 ofassembly 10. Both first tandem pivot door subassembly 22 and secondtandem pivot door subassembly 24 pivot into opening 19 so as to openupstream from an aft end of nacelle 12, such that first tandem pivotdoor subassembly 22 and second tandem pivot door subassembly 24 pivotopen inside of nacelle 12, obstructing flow through bypass duct 26.

Fan bypass stream F₁ is relatively cold air which enters through the fanat the front end of nacelle 12 and passes through bypass duct 26. Whenpivot thrust reverser 20 is in the stowed position, fan bypass stream F₁exits from an aft end of nacelle 12 and can provide a majority of thepropulsion generated by high bypass gas turbine engine 18. However, whenpivot thrust reverser 20 is in the deployed position, as shown in FIGS.1B and 1C, first tandem pivot door subassembly 22 and second tandempivot door subassembly 24 open inside of nacelle 12 and obstruct atleast a portion of the flow of fan bypass stream F₁ through bypass duct26, such that a redirected fan bypass stream F_(1′) no longer exits fromthe aft end of nacelle 12, but is instead diverted in another direction.Redirected fan bypass stream F_(1′) is redirected by deployed pivotthrust reverser 20 to flow in the forward, or upstream, direction shownin FIGS. 1B and 1C. Importantly, pivot thrust reverser 20 is configuredsuch that there need not be any actuators, linkages, or otherobstructions present in F_(1′) flow path when pivot thrust reverser 20is in the deployed position, which could otherwise obstruct the flow ofredirected fan bypass stream F_(1′) in the forward direction, thusreducing the effectiveness of pivot thrust reverser 20. Redirecting fanbypass stream F_(1′) as shown can restrict or prevent fan bypass streamF₁ from providing forward propulsion, but can also actively providedeceleration. Yet, nacelle ventilation stream F₂ and core stream F₃,which flow through the inside of engine 18, can remain substantiallyunobstructed and continue to flow out downstream of engine 18 when pivotthrust reverser 20 is deployed in substantially the same manner as whenpivot thrust reverser 20 is in the stowed position.

Additionally, in the illustrated embodiment, outer panel 32 is largerthan inner panel 31 of first tandem pivot door subassembly 22 and outerpanel 35 is larger than inner panel 34 of second tandem pivot doorsubassembly 24. By using larger outer panels 32 and 35, outer panels 32and 35 not only provide structural support to inner panels 31 and 34respectively, but also take on functional roles. Larger outer panels 32and 35 provide additional guidance, in addition to the guidance providedby inner panels 31 and 34, for redirecting fan bypass stream F_(1′) inthe appropriate forward direction needed to provide deceleration.Consequently, by further guiding redirected fan bypass stream F_(1′) inthe forward direction, pivot thrust reverser 20 operates moreeffectively. Furthermore, larger outer panels 32 and 35 also canfunction as an air break, and thus provide deceleration in addition tothat provided by redirected fan bypass stream F_(1′).

Engine 18 is centered inside nacelle 12, in the illustrated embodiment,and thus is axially aligned with the engine fan at the front end ofnacelle 12 (axis A of FIG. 1A). Upper bi-fi fairing 40 and lower bi-fifairing 42 serve to interconnect nacelle 12 and engine 18, as well asprovide additional stiffness for nacelle 12 and space for wires, tubesand other similar components.

In the illustrated embodiment, as best shown in FIG. 1C, linkage 44provides a hinged connection between inner panel 31 (of first tandempivot door subassembly 22) and pivot axis 45, with linkage 44 fixed tonacelle 12 at pivot axis 45. In the same manner, linkage 46 provides ahinged connection between inner panel 34 (of second tandem pivot doorsubassembly 24) and pivot axis 47, with linkage 46 fixed to nacelle 12at pivot axis 47. Pivot axis 45 of inner panel 31 and pivot axis 47 ofinner panel 34 can be positionally fixed relative to assembly 10,nacelle 12, and/or engine 18. Pivot axis 45 is spaced from inner panel31 and extends from linkage 44 to linkage 48. Similarly, pivot axis 47is spaced from inner panel 34 and extends from linkage 46 to linkage 50.Linkage 48 provides a connection between inner panel 31 and actuator 52,while linkage 50 provides a connection between inner panel 34 andactuator 52.

Outer panel 32 (of first tandem pivot door subassembly 22) is fixed tonacelle 12 at fixed pivot connection points 53 a and 53 b, and pivotsabout pivot axis 49. Points 53 a and 53 b provide hinge points for outerpanel 32 and are located at or near a perimeter of outer panel 32 innacelle 12, between outer surface 14 of nacelle 12 and outer surface 28of bypass duct 26, on pivot axis 49. Outer panel 35 (of second tandempivot door subassembly 24) is fixed to nacelle 12 at fixed pivotconnection points 54 a and 54 b, and pivots about pivot axis 51. Points54 a and 54 b provide hinge points for outer panel 35 and are located ator near a perimeter of outer panel 35 in nacelle 12, between outersurface 14 of nacelle 12 and outer surface 28 of bypass duct 26, onpivot axis 51. Pivot axis 49 of outer panel 32 and pivot axis 51 ofouter panel 35 can each be positionally fixed relative to assembly 10,nacelle 12, and/or engine 18. Pivot axis 49 extends from point 53 a topoint 53 b. Pivot axis 51 extends from point 54 a to point 54 b. Asshown and discussed throughout, inner panels 31 and 34 maintainconnection with outer panels 32 and 35 by sliding rails. As a result,inner panel 31 and outer panel 32 of first tandem pivot door subassembly22 can pivot simultaneously about different pivot axes 45 and 49 withouttranslating relative to those axes 45 and 49. Similarly, inner panel 34and outer panel 35 of second tandem pivot door subassembly 24 can pivotsimultaneously about different pivot axes 47 and 51 without translating.

Actuator 52 pivots both first tandem pivot door subassembly 22 andsecond tandem pivot door subassembly 24 from the stowed position to thedeployed position without translation of first tandem pivot doorsubassembly 22, second tandem pivot door subassembly 24, or any portionof nacelle 12. In the deployed position shown in FIGS. 1B and 1C, firsttandem pivot door subassembly 22 and second tandem pivot doorsubassembly 24 circumferentially surround a portion of inner surface 30of bypass duct 26. Inner panel 31 of first tandem pivot door subassembly22 and inner panel 34 of second tandem pivot door subassembly 24 areeach configured to circumferentially surround inner surface 30 of bypassduct 26 such that an at least partially sealing, mating relationship isformed and there is relatively little leakage of fan bypass stream F₁(the only leakage coming from portions where bypass duct 26 is visible).This means that nearly all of fan bypass stream F₁ is redirected,resulting in a highly efficient pivot thrust reverser 20. Yet, at thesame time entire pivot thrust reverser 20 can be deployed by a singleactuator 52, and therefore, provides a simplified design requiringminimal parts, and thus increases reliability and reduces maintenancecosts.

FIG. 2 is a perspective view of pivot thrust reverser 20 with a singleactuator 52 in a deployed position. Certain assembly 10 components areleft out for simplicity. Included, in addition to that shown anddescribed previously, are third sliding rail 37, fourth sliding rail 38,motor 60, threaded rod 62, threaded knucklehead 64, cutouts 66 and 68,and aft edges 70 and 72. Actuator 52 is located between outer surface 28of bypass duct 26 and outer surface 14 of nacelle 12 (see also FIG. 1C).Actuator 52 can be, for example, a bolt screw linear actuator as shownhere that includes motor 60, threaded rod 62, and threaded knucklehead64. However, various other types of actuators can also be used inalternate embodiments to pivot both first tandem pivot door subassembly22 and second tandem pivot door subassembly 24 between the stowed anddeployed positions. Motor 60 moves threaded knucklehead 64 down threadedrod 62 towards motor 60, and in so doing, pivots inner panel 31 on pivotaxis 45. Then, due to the connection between inner panel 31 and outerpanel 32 by sliding rails 33 and 37, outer panel 32 is simultaneouslymade to pivot on pivot axis 49. At the same time, inner panel 34 is alsopivoted on pivot axis 47, and due to the connection between inner panel34 and outer panel 32 by sliding rails 36 and 38, outer panel 35 issimultaneously made to pivot on pivot axis 51. In this manner, firsttandem pivot door subassembly 22 and second tandem pivot doorsubassembly 24 are pivoted by single actuator 52 about different pivotaxes between stowed and deployed positions without translating (relativeto assembly 10).

Additionally, inner panel 31 of first tandem pivot door subassembly 22contains cutout 66 in aft edge 70 and inner panel 34 of second tandempivot door subassembly 24 contains cutout 68 in aft edge 72. Bothcutouts 66 and 68 are located on upper portions of aft edges 70 and 72respectively. When in the deployed position, as shown here, aft edge 70of inner panel 31 faces aft edge 72 of inner panel 34. As a result,cutout 66 is aligned to face cutout 68 when tandem pivot doorsubassemblies 22 and 24 are deployed, forming an opening in pivot thrustreverser 20 to accommodate engine 18. Both cutout 66 and cutout 68 canbe arc-shaped, resulting in the opening in pivot thrust reverser 20being generally circular in shape. However, in alternative embodiments,cutouts 66 and 68 can have various different shapes and be placed at anylocation on inner panels 31 and 34.

FIG. 3 is an exploded perspective view of inner panel 31 and outer panel32 of first tandem pivot door subassembly 22. Included, in addition tothat shown and described previously, are inward-facing protrusion 67 andside protrusion 69 on outer panel 32. Inner panel 31 is placed on top ofouter panel 32 with the connection made by sliding rails 33 and 37. Inthis embodiment, inward-facing protrusion 67 is of a shape complimentarywith cutout 66 in aft edge 70 of inner panel 31, such that inward-facingprotrusion 67 protrudes into the location of cutout 66 when inner panel31 is placed on top of outer panel 32. Also, side protrusion 69 is of ashape complimentary with curved aft edge 70 of inner panel 31, such thatside protrusion 69 protrudes up from an interface of aft edge 70 andside protrusion 69. Protrusions 67 and 69 then allow first tandem pivotdoor subassembly 22 to both provide a substantially smooth outer surface28 of bypass duct 26 and a complete outer surface 14 of nacelle 12 whenfirst tandem pivot door subassembly 22 is stowed. Consequently, fanbypass stream F₁ experience relatively little turbulence when passingthrough bypass duct 26 at the location where outer surface 28 of bypassduct 26 is formed by stowed first tandem pivot door subassembly 22. Thisallows assembly 10 to produce efficient and effective propulsion evenwith pivot thrust reverser 20 included.

FIGS. 4A and 4B show a plan view of actuator 52 and first tandem pivotdoor subassembly 22 in isolation, with first tandem pivot doorsubassembly 22 pivoted from the stowed to the deployed position. FIG. 4Ashows first tandem pivot door subassembly 22 in the stowed position.FIG. 4B shows first tandem pivot door subassembly 22 pivoted to thedeployed position. Included, in addition to that shown and describedpreviously, are fixed pivot point 45′ and link 80. Fixed pivot point 45′is located on pivot axis 45 (shown in FIG. 1C) and is a pivot connectionpoint about which inner panel 31 rotates. Point 53 b, as discussed forFIG. 1C, is located on pivot axis 49, and is a pivot connection pointabout which outer panel 32 is hinged to nacelle 12 and pivotallyrotates. In this embodiment, point 53 b is located at or near aperimeter of outer panel 32, and more specifically is at or near an aftend of outer panel 32 which can pivot inside of nacelle 12. Link 80provides a connection between threaded knucklehead 64 of actuator 52 andlinkage 48.

As first tandem pivot door subassembly 22 is pivoted to the deployedposition, threaded knucklehead 64 moves down threaded rod 62. Thisforces inner panel 31 to pivot about pivot axis 45 on point 45′, and inturn, due to the connection between inner panel 31 and outer panel 32,forces outer panel 32 to pivot about pivot axis 49 on point 53 b. Outerpanel 32 stops in the position shown in FIG. 4B and does not movefurther along sliding rails 33 and 37 due to point 53 b being fixed tonacelle 12. Therefore, first tandem pivot door subassembly 22 isdeployed by pivoting inner panel 31 and outer panel 32 simultaneouslyabout different pivot points. This allows first tandem pivot doorsubassembly 22 to deploy and avoid interference from nacelle 12 thatotherwise would occur due to the location of first tandem pivot doorsubassembly 22.

FIGS. 5A and 5B show a perspective view of an embodiment of gas turbineengine and nacelle assembly 90 with another embodiment of pivot thrustreverser 92. FIG. 5A shows pivot thrust reverser 92 in a stowedposition, and FIG. 5B shows pivot thrust reverser 92 in a deployedposition. Assembly 90 includes, in addition to that shown and describedpreviously, pivot thrust reverser 92 with first tandem pivot doorsubassembly 94 and second tandem pivot door subassembly 96, inner panel98 and outer panel 99 of first tandem pivot door subassembly 94 (secondtandem pivot door subassembly 96 also has inner and outer panels, butare not visible in these FIGS.). Outer panel 99 is connected to innerpanel 98 by sliding rails, detailed previously. Pivot thrust reverser 92differs from pivot thrust reverser 20 shown previously in that innerpanel 98 is larger than outer panel 99. Here, outer panel 99 serves toprevent interference with nacelle 12 and form both a complete outersurface 14 of nacelle 12 at opening 19 and outer surface 28 of bypassduct 26. Inner panel 98 when stowed also forms both a portion of outersurface 14 of nacelle 12 at opening 19 and outer surface 28 of bypassduct 26. Inner panel 98 and outer panel 99 are flush relative to eachother when stowed. Outer panel 99 can be both shorter in length andwidth than inner panel 98. Also, outer panel 99 can have a curvedforward end when inner panel 98 contains a cutout at an aft edge so asto provide a substantially gap free outer surface 14 of nacelle 12 atopening 19 and outer surface 28 of bypass duct 26.

The present embodiments provide a highly effective thrust reverser foruse in a gas turbine engine. This is because configuring inner panels 31and 34 with cutouts 66 and 68 to surround inner surface 30 of bypassduct 26 as shown allows nearly all of fan bypass stream F₁ to beredirected in the appropriate direction, while at the same timeminimizing the number of components needed to pivot both first andsecond tandem pivot door subassemblies 22 and 24 from the stowed to thedeployed position without interference from nacelle 12. This is turndecreases the weight of thrust reverser 20 while increasing thereliability of thrust reverser 20. Additionally, the design of thrustreverser 20 provides a modular assembly which allows for direct mountingof thrust reverser 20 in position.

Discussion of Possible Embodiments

The following are non-exclusive descriptions of possible embodiments ofthe present invention.

A pivot thrust reverser comprising a first tandem pivot door subassemblycomprising an inner panel and an outer panel wherein the inner panel andthe outer panel are connected by a first sliding rail; and a secondtandem pivot door subassembly comprising an inner panel and an outerpanel, wherein the inner panel and the outer panel are connected by asecond sliding rail.

The pivot thrust reverser of the preceding paragraph can optionallyinclude, additionally and/or alternatively, any one or more of thefollowing features, configurations, and/or additional components:

The inner panel and the outer panel of the first tandem pivot doorsubassembly are configured to rotate simultaneously about differentpivot points, and wherein the inner panel and the outer panel of thesecond tandem pivot door subassembly are configured to rotatesimultaneously about different pivot points.

An actuator configured to pivot both the first tandem pivot doorsubassembly and the second tandem pivot door subassembly from a stowedposition to a deployed position on respective pivot points that are eachpositionally fixed relative to a mounting location.

A pivot point of the inner panel of the first tandem pivot doorsubassembly is located on an arm operatively connected between anactuator and the inner panel of the first tandem pivot door subassembly,and wherein the pivot point of the outer panel of the first tandem pivotdoor subassembly is located at or near a perimeter of the outer panel ofthe first tandem pivot door subassembly.

The actuator is located between a surface of a bypass duct and an outersurface of a nacelle.

The inner panel of the first tandem pivot door subassembly is largerthan the outer panel of the first tandem pivot door subassembly.

The outer panel of the first tandem pivot door subassembly is largerthan the inner panel of the first tandem pivot door subassembly.

The first tandem pivot door subassembly forms both a portion of asurface of a bypass duct and a portion of an outer surface of a nacellewhen in a stowed position.

The inner panel and the outer panel of the first tandem pivot doorsubassembly are connected by a third sliding rail.

A first cutout on the first tandem pivot door subassembly inner panel.

An inward-facing protrusion on the first tandem pivot door subassemblyouter panel, wherein the inward-facing protrusion is of a shapecomplimentary with the first cutout.

A second cutout on the second tandem pivot door subassembly inner panel.

Both the first cutout and the second cutout are each arc-shaped.

A method for reversing thrust of a gas turbine engine, the methodcomprising providing a first tandem pivot door subassembly comprising aninner panel and an outer panel; and connecting the inner panel and theouter panel of the first tandem pivot door subassembly are by a firstsliding rail.

The method of the preceding paragraph can optionally include,additionally and/or alternatively, the following techniques, steps,features and/or configurations:

Rotating the inner panel and the outer panel simultaneously aboutdifferent pivot axes.

Pivotally deploying the first tandem pivot door subassembly from astowed position to a deployed position by an actuator, wherein the innerand outer panels are pivotally deployed by the actuator on respectivepivot points each positionally fixed relative to the gas turbine engine.

Providing a second tandem pivot door subassembly spaced from the firsttandem pivot door subassembly comprising an inner panel and an outerpanel; and connecting the inner panel and the outer panel of the secondtandem pivot door subassembly by a second sliding rail, wherein theinner panel and the outer panel rotate simultaneously about differentpivot points.

The inner panel and the outer panel of the first tandem pivot doorsubassembly are connected by a third sliding rail.

Circumferentially surrounding a portion of an inner surface of a bypassduct with the first tandem pivot door subassembly and the second tandempivot door subassembly when the first tandem pivot door subassembly andthe second tandem pivot door subassembly are in the deployed position;and redirecting a fan bypass stream during engine operation when thefirst tandem pivot door subassembly and the second tandem pivot doorsubassembly are in the deployed position.

Locating the first tandem pivot door subassembly in a location such thatthe first tandem pivot door subassembly forms both a portion of asurface of a bypass duct and a portion of an outer surface of a nacellewhen in the stowed position; and locating the second tandem pivot doorsubassembly in a location such that the second tandem pivot doorsubassembly forms both a portion of the surface of the bypass duct and aportion of the outer surface of the nacelle when in the stowed position.

Any relative terms or terms of degree used herein, such as“substantially”, “essentially”, “generally” and the like, should beinterpreted in accordance with and subject to any applicable definitionsor limits expressly stated herein. In all instances, any relative termsor terms of degree used herein should be interpreted to broadlyencompass any relevant disclosed embodiments as well as such ranges orvariations as would be understood by a person of ordinary skill in theart in view of the entirety of the present disclosure, such as toencompass ordinary manufacturing tolerance variations, incidentalalignment variations, temporary alignment or shape variations induced byoperational conditions, and the like.

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

1. A method for use with a gas turbine engine, the method comprising:providing a first tandem pivot door subassembly comprising an innerpanel and an outer panel; and connecting the inner panel and the outerpanel of the first tandem pivot door subassembly by a first slidingrail.
 2. The method of claim 1, further comprising rotating the innerpanel and the outer panel simultaneously about different pivot axes. 3.The method of claim 2, further comprising pivotally deploying the firsttandem pivot door subassembly from a stowed position to a deployedposition by an actuator, wherein the inner and outer panels arepivotally deployed by the actuator on respective pivot axes eachpositionally fixed relative to the gas turbine engine.
 4. The method ofclaim 3, further comprising: providing a second tandem pivot doorsubassembly spaced from the first tandem pivot door subassemblycomprising an inner panel and an outer panel, and wherein the innerpanel and the outer panel of the second tandem pivot door subassemblyare connected by a second sliding rail, and the step includes rotatingthe inner panel and the outer panel simultaneously about different pivotaxes.
 5. The method of claim 4, wherein the inner panel and the outerpanel of the first tandem pivot door subassembly are connected by athird sliding rail.
 6. The method of claim 4, further comprising:circumferentially surrounding a portion of an inner surface of a bypassduct with the first tandem pivot door subassembly and the second tandempivot door subassembly when the first tandem pivot door subassembly andthe second tandem pivot door subassembly are in the deployed position;and redirecting a fan bypass stream during engine operation when thefirst tandem pivot door subassembly and the second tandem pivot doorsubassembly are in the deployed position.
 7. The method of claim 6,further comprising: locating the first tandem pivot door subassembly ina location such that the first tandem pivot door subassembly forms botha portion of a surface of a bypass duct and a portion of an outersurface of a nacelle when in the stowed position; and locating thesecond tandem pivot door subassembly in a location such that the secondtandem pivot door subassembly forms both a portion of the surface of thebypass duct and a portion of the outer surface of the nacelle when inthe stowed position.